The invention is based on a pressure valve for controlling fluid flow to a fuel injection valve. One such pressure valve, known from an earlier German Patent Application, DE 197 10 891.1, is inserted there into a feed line between a pump work chamber of a fuel injection pump and an injection site of the internal combustion engine to be supplied. This known pressure valve, acting as an equalxe2x80x94pressure valve, has a cylindrical valve housing, in which an axial through bore embodied as a stepped bore is provided. A cylindrical valve body embodied as a tubular stub is inserted from the first face end into the stepped bore in the valve housing. The stepped bore has an axial through conduit, and with an end face protruding into the valve housing, The stepped bore forms a valve seat surrounding the through conduit. An axially displaceable valve member, with a sealing face, comes into contact with this valve seat face by the force of a restoring spring. The movable valve member then protrudes into the through conduit of the valve body and, with an end face that has plunged into the valve body, the end face forms a valve seat face for a further valve member, opening in the opposite direction from the first valve member, of a reverse-flow valve disposed inside the valve body.
The cylindrical valve body, in the known pressure valve, is press-fitted via its radial circumferential surface into the through bore in the valve housing. This press-fit connection, however, has the disadvantage that the surfaces of the valve body and of the through bore in the valve housing must be machined very precisely, which entails very major production effort and expense with respect to the tolerance at these fitting faces. Furthermore, a valve body press-fitted into the valve housing in this way is very difficult to dismantle later, so that replacing the pressure valve components for repair purposes later on can be accomplished only at relatively major effort and expense. As an alternative to this, it is known in pressure valves for the valve body to be screwed into the valve housing by means of a thread. This screw connection, however, is also relatively complicated from a production standpoint and moreover weakens the high-pressure strength of the components. The known pressure valves thus have the disadvantage that axially securing the valve body and the valve housing against unintended slipping out can be achieved only at relatively major effort and expense in production, or at the cost of poor dismantling capability.
The pressure valve according to the invention has the advantage over the prior art that axially securing the valve body in the valve housing can be achieved very simply from a production standpoint, and furthermore assures easy dismantling of the two components. To that end, the valve body is advantageously secured axially in the valve housing by means of a detent connection. This detent connection is formed, in a manner similar to a tongue-and-groove connection, by means of an annular collar protruding radially from the circumferential wall of the cylindrical valve body and a receiving annular groove in the wall of the bore of the valve housing. The receiving annular groove is spaced apart in the bore wall of the valve housing from the axial end face toward the valve body, and this intermediate region of the bore has a diameter that is less than the outside diameter of the annular collar, acting as a pressure collar on the valve body. On the opposite side, the receiving annular groove of the valve housing bore is adjoined by a further bore portion, whose diameter is again less than the diameter of the annular collar on the valve body; the two bore portions adjoining the receiving annular groove of the valve housing bore preferably have the same inside diameter. The annular collar on the valve body is also spaced apart from the end faces of the valve body by two shaft regions whose diameter is less than the diameter of the bore regions of the valve housing bore that adjoin the receiving annular groove on both ends. In addition, on its end remote from the valve housing, the valve body has a head piece of enlarged cross section, which is spaced apart from the annular collar by the smaller-diameter shaft region, and whose diameter is greater than the diameter of the bore in the valve housing and is also greater than the annular collar. The axial length of the receiving annular groove in the valve housing bore is greater than the axial length of the annular collar on the valve body. The receiving annular groove is embodied and disposed such that the head piece on the valve body, when the annular collar protrudes into the receiving annular groove, can be brought into contact with the end face of the valve housing. When the annular collar is protruding into the receiving annular groove, it is furthermore possible, with contact of the annular collar on the end toward the valve body of the receiving annular groove, to establish an axial spacing between the end face of the valve housing and the head piece on the valve body. This disposition and embodiment of the receiving annular groove in cooperation with the annular collar on the valve body provides a secure, sealing contact of the valve body head piece with the end face of the valve housing and an initially easy retraction of the valve body out of the valve housing bore, at least far enough that a puller tool can engage the head piece of the valve body from behind. Because of this improved engagement of a puller tool, the valve body can then simply be pulled out of the valve housing. The sealing between the valve body and the valve housing can advantageously be improved by providing that on the annular end face, toward the valve housing, of the head piece on the valve body, or on its end face that has dipped into the valve housing, a biting edge is provided, which cooperates sealingly with a corresponding counterpart face on the valve housing. The axial sealing force is brought to bear either while the pressure valve is being built into a corresponding component, or by an external, separate component.
Another advantage is attained in that when the valve body is inserted or press-fitted into the bore of the valve housing, the body edges to be overtaken that are located on the annular collar, the receiving annular groove or the end face of the valve housing are chamfered, to prevent canting of or damage to the components in the press-fitting process. Furthermore, even very slight differences in diameter between the faces on the valve body and on the valve housing suffice to assure reliable function.
The pressure valve of the invention, in the exemplary embodiment, is embodied as an equal-pressure valve, and the valve member guided axially displaceably in a through bore in the valve body that forms a through conduit receives a further reverse-flow valve that opens counter to the opening direction of the valve member. The axial ends of the through bore in the valve housing are advantageously embodied as line connections, which can be adjoined for example by a feed line to a fuel injection valve or on the other hand a pump work chamber of a high-pressure fuel pump. The embodiment according to the invention of the axial securing of the valve body inside the valve housing is not, however, limited to this type of equal-pressure valve but instead can be used in all similar valve types, in which a tubular component is to be axially secured in a bore of a second component. Alternatively, a transposition would be possible such that the radially protruding annular collar is provided on the bore wall and the radially inward-oriented receiving annular groove is provided on the valve body to be inserted.
Further advantages and advantageous refinements of the subject of the invention can be learned from the drawing, description and claims.